The Health Benefits of Larch Arabinogalactan

A supplement used by some looking to boost their immune system

Larch Arabinogalactan powder and capsules

 Verywell / Anastasia Tretiak

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Larch arabinogalactan is a natural substance sourced from the wood of the larch tree (Larix occidentalis) that is thought to offer a number of health benefits. Chief among these is the stimulation of the immune system and the prevention of viral and bacterial infections.

Arabinogalactan is a fiber found in many plants, but it occurs in especially high concentrations in the larch tree. Larch arabinogalactan is widely available in dietary supplement form.

Health Benefits

Larch arabinogalactan is a complex carbohydrate that alternative practitioners believe can protect against common and uncommon infections. It is thought to stimulate the immune system by increasing the amount of probiotic bacteria in the gut as it undergoes fermentation.

For reasons not entirely understood, this action triggers a dramatic increase in defensive antibodies, including immunoglobulin G (IgG), as well as inflammatory proteins such as tumor necrosis factor (TNF).

In addition to improving digestion, larch arabinogalactan is believed by some to prevent or treat the following health conditions:

As is often the case with alternative remedies, some of the claims about larch arabinogalactan are better supported by research than others.

Here is a look at some key findings from studies on the benefits of larch arabinogalactan.

Common Cold

Larch arabinogalactan has been used for centuries in Native American cultures as a means of defending against the common cold. This use has been evaluated in a number of studies, including a placebo-controlled trial published in Current Medical Research and Opinion.

The study was conducted during the cold season of 2010/2011 with 199 healthy volunteers who had reported at least three upper respiratory tract infections in the previous year. The participants were randomly given either 4.5 gram (g) of an arabinogalactan preparation called ResistAid or a placebo. Outcomes were measured by a 10-point questionnaire in which cold symptoms were rated on a scale from 0 to 3.

After 12 weeks, the researchers reported that the group given arabinogalactan had 23% fewer colds than those given a placebo. However, those in the arabinogalactan group who experienced colds reported far worse symptoms.

The conclusions, while interesting, were limited by the highly subjective nature of the questionnaire and the fact that the research was funded by the manufacturer of ResistAid.

Vaccine Enhancement

It has been proposed that larch arabinogalactan can bolster the effectiveness of vaccines by amplifying the immunological response. This effect could theoretically increase the effectiveness of vaccines that sometimes fail in very young children or older adults.

In a 2010 study published in Nutrition Journal, 45 healthy adults were given a placebo or a daily dose of 4.5 g of ResistAid for 72 days (starting 30 days prior to influenza vaccination). Scientists found that those treated with ResistAid experienced a greater antibody response after the flu shot than their counterparts.

According to the researchers, the ResistAid group had far higher levels of pneumonia-specific IgG antibodies than those provided the placebo. The results are significant given that IgG binds disease-causing pathogens (such as viruses, bacteria, and fungi) and protects the body against infection.

The same lab reported similar findings when ResistAid was given in a combination with a tetanus vaccine.

Despite the promising findings, there is no way to predict how much more effective the vaccines may be when combined with ResistAid. In the end, an increased IgG response does not inherently confer to a lower incidence of infection.

At this stage, the protective benefit is largely speculative. Further research is needed.


Claims that larch arabinogalactan can prevent cancer are, at best, exaggerated. The hypothesis was largely spurred by misconceptions about arabinogalactan's role in stimulating tumor necrosis factor-alpha (TNFa).

Despite its name, TNFa neither acts upon nor causes cancer but, instead, triggers an inflammatory response to help neutralize disease-causing pathogens. If anything, increased production of TNF-a is linked to the development of certain cancers.

With that said, arabinogalactan may aid in the treatment of cancer by preventing the depletion of white blood cells that commonly occurs during chemotherapy.

According to research published in Evidence-Based Complementary and Alternative Medicine, lab mice treated for colon cancer with the chemotherapy drug 5-fluorouracil (5-FU) experienced increased production of white blood cells, called leukocytes, after using an arabinogalactan extract.

Leukopenia, the deficiency of leukocytes, is a common but serious side effect of 5-FU and one that can cause fever, sweating, chills, and an increased risk of infection. Further research is needed to determine whether arabinogalactan can help humans with cancer avoid chemo-induced leukopenia.

Possible Side Effects

Little is known about the long-term safety of larch arabinogalactan. When used occasionally, the supplement may cause mild gastrointestinal side effects, including bloating, flatulence, and cramps. If overused, larch arabinogalactan may cause diarrhea.

People allergic to larch tree and other members of the pine family may also be allergic to larch arabinogalactan, although this is uncommon.

There is also concern that larch arabinogalactan may trigger a flare-up of symptoms in people with autoimmune diseases such as lupus, multiple sclerosis, or rheumatoid arthritis. The concern is largely speculative but one worthy of consideration given the way in which arabinogalactan incites an immune response.

Larch arabinogalactan should also be used with caution in organ transplant recipients in whom the substance may increase the risk of organ rejection.

To be safe, avoid larch arabinogalactan in any form if you are on any of the following immunosuppressive drugs:

The safety of larch arabinogalactan in children, pregnant women, or nursing mothers has not been established. Because of this, it should not be used without direct supervision from a qualified pediatrician or OB/GYN.

Always advise your doctor about any and all supplements and drugs you are taking, whether prescription or over-the-counter.

Larch Arabinogalactan capsules

 Verywell / Anastasia Tretiak

Dosage and Preparation

Larch arabinogalactan supplements and powdered extracts are widely available online and in many natural foods stores, drugstores, and shops specializing in dietary supplements.

There are no guidelines for the appropriate use of larch arabinogalactan. Depending on the manufacturer, doses can range anywhere from 30 to 500 milligrams (mg). Studies have suggested that daily doses of up to 4.5 g (4,500 mg) have been used safely in adults.

As a rule of thumb, it is always better to start with a smaller dose of larch arabinogalactan, increasing it incrementally as tolerated. Higher doses do not inherently confer to better results and may, in fact, increase the risk of diarrhea.

Dietary supplements like larch arabinogalactan are not strictly regulated in the United States. To better ensure quality and safety:

  • Opt for brands that are certified organic by the U.S. Department of Agriculture (USDA).
  • Check the product label to ensure there are no other added ingredients or fillers. Brands marked "pure" should not contain anything but larch arabinogalactan extract.
  • Be sure that the species name Larix occidentalis is printed on the product label. This is because North American larch is a different species than European larches, the latter of which only have a fraction of the arabinogalactan content.

Larch arabinogalactan supplements and powders are best taken in the morning, the fiber content of which can better ensure bowel regularity. If you experience flatulence or bloating, taking the dose right before bedtime can sometimes help.

Larch arabinogalactan powder is typically mixed with water or juice or stirred into smoothies, yogurt, or protein shakes.

Other Questions

What does larch arabinogalactan taste like?
Larch arabinogalactan has a slightly sweet flavor and a subtle pine-like aroma. In fact, it is commonly used in food production as a sweetener (as well as a stabilizer and thickening agent).

Are there other sources of arabinogalactan?
North American larch trees have the highest concentration of arabinogalactan of any source, accounting for as much as 35% of the dried heartwood weight. There are other sources for arabinogalactan, though with vastly smaller quantities. These include:

  • Carrot
  • Radish
  • Pear
  • Corn
  • Wheat
  • Leek seed
  • Tomato
  • The herbs echinacea, Curcuma longa, and Angelica acutiloba
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Article Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Udani JK. Immunomodulatory effects of ResistAid: a randomized, double-blind, placebo-controlled, multidose studyJ Am Coll Nutr. 2013;32(5):331–8. doi:10.1080/07315724.2013.839907

  2. Dion C, Chappuis E, Ripoll C. Does larch arabinogalactan enhance immune function? A review of mechanistic and clinical trials. Nutr Metab (Lond). 2016;13:28. doi:10.1186/s12986-016-0086-x.

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